Effects of the porosity in uranium dioxide on microacoustic and elastic properties

The laws of variation of the Rayleigh velocity and the longitudinal velocit y of the acoustic waves as a function of the porosity in uranium oxide UO2 has been proven through local acoustic measurements carried out, respective ly, by acoustic microscopy and by microechography. The variations of the el astic constants with porosity have been deduced from these laws. Thanks to these results, the role of porosity can be separated and the part of the ot her factors in the alteration of elastic properties of nuclear fuel materia ls can be highlighted. These new investigation methods, combined with micro indentation techniques are expected to be helpful in improving the nuclear fuel material characterisation at high burn-up. (C) 2000 Elsevier Science B .V. All rights reserved.